[WATCHDOG] at32ap700x_wdt.c - Add nowayout + MAGICCLOSE features

Add nowayout + MAGICCLOSE features.

Signed-off-by: Hans-Christian Egtvedt <hcegtvedt@atmel.com>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Cc: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 53 insertions, 11 deletions

diff --git a/drivers/char/watchdog/at32ap700x_wdt.c b/drivers/char/watchdog/at32ap700x_wdt.c
index 6e7c9588b1b9..fcd55c600b87 100644
--- a/drivers/char/watchdog/at32ap700x_wdt.c
+++ b/drivers/char/watchdog/at32ap700x_wdt.c
@@ -30,6 +30,11 @@ MODULE_PARM_DESC(timeout,
                 "Timeout value. Limited to be 1 or 2 seconds. (default="
                 __MODULE_STRING(TIMEOUT_DEFAULT) ")");
 
+static int nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
 /* Watchdog registers and write/read macro */
 #define WDT_CTRL                0x00
 #define WDT_CTRL_EN                0
@@ -54,6 +59,7 @@ struct wdt_at32ap700x {
 };
 
 static struct wdt_at32ap700x *wdt;
+static char expect_release;
 
 /*
  * Disable the watchdog.
@@ -102,15 +108,19 @@ static int at32_wdt_open(struct inode *inode, struct file *file)
 }
 
 /*
- * Close the watchdog device. If CONFIG_WATCHDOG_NOWAYOUT is _not_ defined then
- * the watchdog is also disabled.
+ * Close the watchdog device.
  */
 static int at32_wdt_close(struct inode *inode, struct file *file)
 {
-#ifndef CONFIG_WATCHDOG_NOWAYOUT
-        at32_wdt_stop();
-#endif
+        if (expect_release == 42) {
+                at32_wdt_stop();
+        } else {
+                dev_dbg(wdt->miscdev.parent,
+                        "Unexpected close, not stopping watchdog!\n");
+                at32_wdt_pat();
+        }
         clear_bit(1, &wdt->users);
+        expect_release = 0;
         return 0;
 }
 
@@ -136,7 +146,9 @@ static int at32_wdt_settimeout(int time)
 
 static struct watchdog_info at32_wdt_info = {
         .identity       = "at32ap700x watchdog",
-        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+        .options        = WDIOF_SETTIMEOUT |
+                          WDIOF_KEEPALIVEPING |
+                          WDIOF_MAGICCLOSE,
 };
 
 /*
@@ -191,10 +203,35 @@ static int at32_wdt_ioctl(struct inode *inode, struct file *file,
         return ret;
 }
 
-static ssize_t at32_wdt_write(struct file *file, const char *data, size_t len,
-                                loff_t *ppos)
+static ssize_t at32_wdt_write(struct file *file, const char __user *data,
+                                size_t len, loff_t *ppos)
 {
-        at32_wdt_pat();
+        /* See if we got the magic character 'V' and reload the timer */
+        if (len) {
+                if (!nowayout) {
+                        size_t i;
+
+                        /*
+                         * note: just in case someone wrote the magic
+                         * character five months ago...
+                         */
+                        expect_release = 0;
+
+                        /*
+                         * scan to see whether or not we got the magic
+                         * character
+                         */
+                        for (i = 0; i != len; i++) {
+                                char c;
+                                if (get_user(c, data+i))
+                                        return -EFAULT;
+                                if (c == 'V')
+                                        expect_release = 42;
+                        }
+                }
+                /* someone wrote to us, we should pat the watchdog */
+                at32_wdt_pat();
+        }
         return len;
 }
 
@@ -255,8 +292,9 @@ static int __init at32_wdt_probe(struct platform_device *pdev)
 
         platform_set_drvdata(pdev, wdt);
         wdt->miscdev.parent = &pdev->dev;
-        dev_info(&pdev->dev, "AT32AP700X WDT at 0x%p, timeout %d sec\n",
-                wdt->regs, wdt->timeout);
+        dev_info(&pdev->dev,
+                "AT32AP700X WDT at 0x%p, timeout %d sec (nowayout=%d)\n",
+                wdt->regs, wdt->timeout, nowayout);
 
         return 0;
 
@@ -271,6 +309,10 @@ err_free:
 static int __exit at32_wdt_remove(struct platform_device *pdev)
 {
         if (wdt && platform_get_drvdata(pdev) == wdt) {
+                /* Stop the timer before we leave */
+                if (!nowayout)
+                        at32_wdt_stop();
+
                 misc_deregister(&wdt->miscdev);
                 iounmap(wdt->regs);
                 kfree(wdt);